This is from 1961:

I am of the opinion that it is not impossible to achieve at least an 80% survival over a period of years, and with proper methods, 80% of the surviving colonies can be brought through  sufficiently strong to be split at least once.

The table following this article, taken from an address by Mr. H. T. Luther of the Lethbridge Experimental Farm, to the Alberta Beekeepers’ Association Convention, is somewhat of an eye-opener. Please take special note of the years in which these tests were conducted. Wintering bees successfully was a matter of life and death, or perhaps I should say, remaining a beekeeper or looking for another occupation, at that time.

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comment:
I think it's telling that the author suggests that 20% loss would be an improvement over what must have been losses of 30% or more. People have suggested that in recent years beekeepers have experienced unprecedented and unsustainable losses. The above suggests that losing a third of the colonies was routine in the 1960s.

The aforementioned table shows "During 15 years the following figures were accumulated:"

Single colony packed in a case. Number of colonies = 118. Survival = 70%
2 colonies packed in 1 case. No. = 146. Survival = 77%
4 colonies packed in 1 case. No. = 312. Survival = 96%
Single colony wrapped in tarpaper. No. = 229. Survival = 90%

Of interest was the cost per hive of these treatments. A packing case for one = $3.65 (in 1961). Tarpaper for one = 20 cents.
It's also worth noting at the time prices for package bees in 1961 were $3.60 up.

PLB

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